Abstract
Background: Enterobacteriaceae are major players in the spread of resistance to β-lactam antibiotics through the action of CTX-M β-lactamases. We aimed to analyze the diversity and genetic characteristics of ESBL-producing Escherichia coli and Klebsiella pneumoniae isolates from patients in a Northern Portuguese hospital. Methods: A total of 62 cefotaxime/ceftazidime-resistant E. coli (n = 38) and K. pneumoniae (n = 24) clinical isolates were studied. Identification was performed by MALDI-TOF MS. Antimicrobial susceptibility testing against 13 antibiotics was performed. Detection of ESBL-encoding genes and other resistance genes, phylogenetic grouping, and molecular typing (for selected isolates) was carried out by PCR/sequencing. Results: ESBL activity was detected in all 62 E. coli and K. pneumoniae isolates. Most of the ESBL-producing E. coli isolates carried a blaCTX-M gene (37/38 isolates), being blaCTX-M-15 predominant (n = 32), although blaCTX-M-27 (n = 1) and blaCTX-M-1 (n = 1) were also detected. Two E. coli isolates carried the blaKPC2/3 gene. The lineages ST131-B2 and ST410-A were detected among the ESBL-producing blood E. coli isolates. Regarding the 24 ESBL-producing K. pneumoniae isolates, 18 carried a blaCTX-M gene (blaCTX-M-15, 16 isolates; blaCTX-M-55, 2 isolates). All K. pneumoniae isolates carried blaSHV genes, including ESBL-variants (blaSHV-12 and blaSHV-27, 14 isolates) or non-ESBL-variants (blaSHV-11 and blaSHV-28, 10 isolates); ten K. pneumoniae isolates also carried the blaKPC2/3 gene and showed imipenem-resistance. ESBL-positive E. coli isolates were ascribed to the B2 phylogenetic group (82%), mostly associated with ST131 lineage and, at a lower rate, to ST410/A. Regarding K. pneumoniae, the three international lineages ST15, ST147, and ST280 were detected among selected isolates. Conclusions: Different ESBL variants of CTX-M (especially CTX-M-15) and SHV-type (specially SHV-12) were detected among CTX/CAZR E. coli and K. pneumoniae isolates, in occasions associated with carbapenemase genes (blaKPC2/3 gene).
Highlights
Escherichia coli is a commensal microorganism of the intestinal microbiota of humans and animals
Klebsiella pneumoniae can be found in the intestinal microbiota of healthy humans and animals may cause life-threatening infections; it is considered a major opportunistic pathogen implicated in nosocomial infections, especially in patients of intensive-care units (UCIs) and in immunocompromised hosts with severe underlying diseases
The purpose of the present study is to expand this previous work by analyzing in the same hospital the ESBLs types and the main associated resistance mechanisms in broad-spectrum cephalosporin-resistant K. pneumoniae isolates obtained from different clinical origins, and in Escherichia coli isolates obtained from blood and urine samples; the genetic lineages of selected isolates were the aim of this research
Summary
Escherichia coli is a commensal microorganism of the intestinal microbiota of humans and animals It is involved in a great variety of intestinal and extra-intestinal infections as an opportunistic pathogen, including septicemia, as well as urinary and wound infections, among others; this microorganism presents a high facility to acquire antimicrobial-resistant genes [1,2]. Klebsiella pneumoniae can be found in the intestinal microbiota of healthy humans and animals may cause life-threatening infections; it is considered a major opportunistic pathogen implicated in nosocomial infections (as is the case of pneumonia or bloodstream infections), especially in patients of intensive-care units (UCIs) and in immunocompromised hosts with severe underlying diseases. A previous report created by our group showed the presence of ESBL-producing E. coli among healthy and sick cats [14] and dogs [15] in Portugal
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